Abstract：
A deep speciation study on L-carnosine (CAR) and Pb2+ system was performed in aqueous solution with the aim to assess its potential use as a sequestering agent of metal cation. To determine the best conditions for Pb2+ complexation, potentiometric measurements were carried out over a wide range of ionic strength (0.15 ≤ I/≤ 1 mol/L) and temperature (15 ≤ T/°C ≤ 37), and thermodynamic interaction parameters (logβ, ΔH, ΔG and TΔS) were determined. The speciation studies allowed us to simulate sequestration ability of CAR toward Pb2+ under different conditions of pH, ionic strength and temperature and to establish a priori the conditions for the best removal performance, i.e., pH > 7 and I = 001 mol/L. This preliminary investigation was very useful in optimizing removal procedures and limiting subsequent experimental measurements for adsorption tests. Therefore, to exploit the binding ability of CAR for Pb2+ removal from aqueous solutions, CAR was covalently grafted on an azlactone-activated beaded-polyacrylamide resin (AZ) using an efficient click coupling reaction (78.3% of coupling efficiency). The carnosine-based resin (AZCAR) was analyzed by ThermoGravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and Differential Thermal Analysis (DTA). Morphology, surface area and pore size distribution were studied through a combination of Scanning Electron Microscope (SEM) and adsorption/desorption of N2 analyses according to the Brunauer-Emmett-Teller (BET) and Barret-Johner-Halenda (BJH) approaches. The adsorption capacity of AZCAR toward Pb2+ was investigated under conditions simulating the ionic strength and pH of different natural waters. The time needed to reach equilibrium in the adsorption process was 24 h, and the best performance was obtained at pH > 7, typical of most natural waters, with removal efficiency ranging from 90.8% (at I = 0.7 mol/L) to 99.0 (at I = 0.001 mol/L).
摘要：
在水溶液中对L-肌肽（CAR）和Pb2系统进行了深入的形态研究，目的是评估其作为金属阳离子螯合剂的潜在用途。为了确定Pb2+络合的最佳条件，在很宽的离子强度（0.15≤I/≤1mol/L）和温度（15≤T/°C≤37）范围内进行电位测量，和热力学相互作用参数(logβ，ΔH,确定ΔG和TΔS)。形态研究使我们能够模拟不同pH条件下CAR对Pb2的螯合能力，离子强度和温度,并建立了最佳去除性能的先验条件,即，pH>7，I=001mol/L此初步研究对于优化去除程序和限制后续吸附测试的实验测量非常有用。因此,为了利用CAR从水溶液中去除Pb2+的结合能力，使用有效的点击偶联反应(偶联效率的78.3%),将CAR共价接枝到乙内酯活化的珠状聚丙烯酰胺树脂(AZ)上。通过热重分析（TGA）分析基于肌肽的树脂（AZCAR），差示扫描量热法(DSC)和差热分析(DTA)。形态学,根据Brunauer-Emmett-Teller（BET）和Barret-Johner-Halenda（BJH）方法，通过扫描电子显微镜（SEM）和N2吸附/解吸分析的组合研究了表面积和孔径分布。在模拟不同天然水的离子强度和pH值的条件下，研究了AZCAR对Pb2的吸附能力。在吸附过程中达到平衡所需的时间为24h，并且在pH>7时获得最佳性能，这是大多数天然水域的典型特征，去除率为90.8%(I=0.7mol/L)至99.0(I=0.001mol/L)。
